George Tsangaroulis, DDS

There are other factors besides material selection, although it is very important.  Tooth position, alignment, extent of overbite and presence of tooth wear and grinding are significant factors as well.  I would suggest having a diagnostic waxup or prototype model of your outcome which takes into account contours and how your teeth fit together when you bite and grind in order to minimize collisions and chipping long term.  This way you can also "test drive" a replica of the prototype in the mouth with temporary material to have more predictability prior to proceeding to the permanent restorations.  In terms of material, emax in my opinion has the best combination of strength, durability and esthetics for veneers.  But by having a knowledgeable clinician with a skilled laboratory technician and a good waxup, this could potentially allow you to have a weaker, but more esthetic material such as feldspathic porcelain.

I would recommend for a skilled and knowledgeable dentist to provide a facial analysis to first come up with a proper diagnosis so that you understand the root of the problem.  Other than having a hyperactive lip, you may have something called vertical maxillary excess which can be determined by measuring the upper, middle and lower thirds of your face.  If the lower third is greater than the middle third, you can have excessive gum display.  This can be treated by jaw surgery, crown lengthening (gum recontouring), or possibly botox which may not be as effective.  

I would definitely consider orthodontics to get the teeth in proper position and alignment while also addressing your deep bite.  Your dentist should also perform a facial analysis to determine your lip length and lip mobility.  If you have a hypermobile lip you can have excessive gum display when you smile.  Botox treatment can help improve this also.

It is unlikely, but yes it is possible depending on how long ago the veneers were done and your home care routine and brushing technique.  If you are not brushing well at the gumline, debris and plaque can remain and cause decay.  Keep in mind however that cavities do not develop overnight, it takes time.  

Did you have any pain or discomfort with the temporaries?  I would have your bite checked again, there should be even and simultaneous contacts when you bite.  Also check the contacts between the teeth to make sure all the residual cement was cleaned out.